Hemoglobin display and patient treatment

ABSTRACT

The present disclosure describes embodiments of a patient monitoring system and methods that include the measure and display of hemoglobin statistics. In an embodiment, total hemoglobin trending is displayed over a period of time. Statistics can include frequency domain analysis, which may be unique for each patient monitored. The total hemoglobin trending and/or statistics can further be used to help control the treatment of a patient, such as being used to control IV administration.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/571,591, filed Sep. 16, 2019, entitled “HEMOGLOBIN DISPLAY ANDPATIENT TREATMENT,” which is a continuation of U.S. application Ser. No.15/789,357, filed Oct. 20, 2017, entitled “HEMOGLOBIN DISPLAY ANDPATIENT TREATMENT,” which is a continuation of U.S. patent applicationSer. No. 15/184,950, filed Jun. 16, 2016, entitled “HEMOGLOBIN DISPLAYAND PATIENT TREATMENT,” which is a continuation of U.S. patent Ser. No.14/714,691, filed May 18, 2015, now U.S. Pat. No. 9,370,325, entitled“HEMOGLOBIN DISPLAY AND PATIENT TREATMENT,” which is a continuation ofU.S. patent application Ser. No. 14/064,026, filed Oct. 25, 2013, nowU.S. Pat. No. 9,037,207, entitled “Hemoglobin Display and PatientTreatment,” which is a continuation of U.S. patent application Ser. No.12/783,436, filed May 19, 2010, now U.S. Pat. No. 8,571,619, entitled“Hemoglobin Display and Patient Treatment,” which claims prioritybenefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Nos.61/180,018 filed May 20, 2009, entitled “Hemoglobin Display,” and61/221,435 entitled “Hemoglobin Display and Patient Treatment,” filedJun. 29, 2009. The present application incorporates the disclosures ofthe foregoing applications herein by reference in their entireties.

FIELD OF THE INVENTION

The present disclosure relates to the processing and display of ahemoglobin measurement.

BACKGROUND

During patient care, it is important to know the composition of thepatient's blood. Knowing the composition of the patient's blood canprovide an indication of the patient's condition, assist in patientdiagnosis, and assist in determining a course of treatment. One bloodcomponent in particular, hemoglobin, is very important. Hemoglobin isresponsible for the transport of oxygen from the lungs to the rest ofthe body. If there is insufficient total hemoglobin or if the hemoglobinis unable to bind with or carry enough oxygen, then the patient cansuffocate. In addition to oxygen, other molecules can bind tohemoglobin. For example, hemoglobin can bind with carbon monoxide toform carboxyhemoglobin. When other molecules bind to hemoglobin, thehemoglobin is unable to carry oxygen molecules, and thus the patient isdeprived of oxygen. Also, hemoglobin can change its molecular form andbecome unable to carry oxygen, this type of hemoglobin is calledmethemoglobin.

Pulse oximetry systems for measuring constituents of circulating bloodhave gained rapid acceptance in a wide variety of medical applicationsincluding surgical wards, intensive care and neonatal units, generalwards, home care, physical training, and virtually all types ofmonitoring scenarios. A pulse oximetry system generally includes anoptical sensor applied to a patient, a monitor for processing sensorsignals and displaying results and a patient cable electricallyinterconnecting the sensor and the monitor. A pulse oximetry sensor haslight emitting diodes (LEDs), typically at least one emitting a redwavelength and one emitting an infrared (IR) wavelength, and aphotodiode detector. The emitters and detector are attached to a patienttissue site, such as a finger. The patient cable transmits drive signalsto these emitters from the monitor, and the emitters respond to thedrive signals to transmit light into the tissue site. The detectorgenerates a signal responsive to the emitted light after attenuation bypulsatile blood flow within the tissue site. The patient cable transmitsthe detector signal to the monitor, which processes the signal toprovide a numerical readout of physiological parameters such as oxygensaturation (SpO2) and pulse rate.

Standard pulse oximeters, however, are unable to provide an indicationof how much hemoglobin is in a patient's blood or whether othermolecules were binding to hemoglobin and preventing the hemoglobin frombinding with oxygen. Care givers had no alternative but to measure mosthemoglobin parameters, such as total hemoglobin, methemoglobin andcarboxyhemoglobin by drawing blood and analyzing it in a lab. Given thenature of non-continuous blood analysis in a lab, it was widely believedthat total hemoglobin did not change rapidly.

Advanced physiological monitoring systems utilize multiple wavelengthsensors and multiple parameter monitors to provide enhanced measurementcapabilities including, for example, the measurement ofcarboxyhemoglobin (HbCO), methemoglobin (HbMet) and total hemoglobin(Hbt or tHb). Physiological monitors and corresponding multiplewavelength optical sensors are described in at least U.S. patentapplication Ser. No. 11/367,013, filed Mar. 1, 2006 and titled MultipleWavelength Sensor Emitters and U.S. patent application Ser. No.11/366,208, filed Mar. 1, 2006 and titled Noninvasive Multi-ParameterPatient Monitor, both assigned to Masimo Laboratories, Irvine, Calif.(“Masimo Labs”) and both incorporated by reference herein. Pulseoximeters capable of reading through motion induced noise are disclosedin at least U.S. Pat. Nos. 6,770,028, 6,658,276, 6,650,917, 6,157,850,6,002,952, 5,769,785, and 5,758,644; low noise pulse oximetry sensorsare disclosed in at least U.S. Pat. Nos. 6,088,607 and 5,782,757; all ofwhich are assigned to Masimo Corporation, Irvine, Calif. (“Masimo”) andare incorporated by reference herein.

Further, physiological monitoring systems that include low noise opticalsensors and pulse oximetry monitors, such as any of LNOP® adhesive orreusable sensors, SofTouch™ sensors, Hi-Fi Trauma™ or Blue™ sensors; andany of Radical®, SatShare™, Rad-9™, Rad-S™, Rad-5v™ or PPO+™ Masimo SET®pulse oximeters, are all available from Masimo. Physiological monitoringsystems including multiple wavelength sensors and correspondingnoninvasive blood parameter monitors, such as Rainbow™ adhesive andreusable sensors and Rad-57™, Rad-87™ and Radical-7™ monitors formeasuring SpO2, pulse rate, perfusion index, signal quality, HbCO andHbMet among other parameters are also available from Masimo.

SUMMARY

The present disclosure provides for the measurement, display andanalysis of hemoglobin content in living patients. It has beendiscovered that, contrary to the widely held understanding that totalhemoglobin does not change rapidly, total hemoglobin fluctuates overtime. In an embodiment, the trend of a patient's continuous totalhemoglobin (tHb or Hbt) measurement is displayed on a display. In anembodiment, the trend of the total hemoglobin is analyzed through, forexample, a frequency domain analysis to determine patterns in thepatient hemoglobin fluctuation. In an embodiment, a frequency domainanalysis is used to determine a specific signature of the hemoglobinvariability specific to a particular patient. In some embodiments, thespecific elements of a patient's hemoglobin variability may provideinformation useful for the diagnosis of specific diseases, including,for example, diseases that affect hemoglobin and red blood cell functionsuch as sickle cell anemia.

Additionally, exemplary uses of these hemoglobin readings areillustrated in conjunction with dialysis treatment and bloodtransfusions.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings and following associated descriptions are provided toillustrate embodiments of the present disclosure and do not limit thescope of the claims. Corresponding numerals indicate correspondingparts, and the leading digit of each numbered item indicates the firstfigure in which an item is found.

FIG. 1 illustrates a perspective view of a patient monitoring system inaccordance with an embodiment of the disclosure.

FIG. 2 illustrates a block drawing of a patient monitoring system inaccordance with an embodiment of the disclosure.

FIG. 3 illustrates a planar view of a patient monitor displaying asample graph of total hemoglobin versus time as may be displayed by apatient monitoring system in accordance with an embodiment of thedisclosure.

FIG. 4 illustrates a planar view of a patient monitor displaying a graphof a frequency domain analysis.

FIG. 5 illustrates a block diagram of a method of monitoring andanalyzing a patient's total hemoglobin levels.

FIG. 6 illustrates a perspective view of a patient monitoring system andblood manipulation device, such as a dialysis machine, in accordancewith an embodiment of the disclosure.

FIG. 7 illustrates a block diagram of a patient monitoring system,including transfusion capabilities in accordance with an embodiment ofthe disclosure.

DETAILED DESCRIPTION

Aspects of the disclosure will now be set forth in detail with respectto the figures and various embodiments. One of skill in the art willappreciate, however, that other embodiments and configurations of thedevices and methods disclosed herein will still fall within the scope ofthis disclosure even if not described in the same detail as some otherembodiments. Aspects of various embodiments discussed do not limit thescope of the disclosure herein, which is instead defined by the claimsfollowing this description.

Turning to FIG. 1, an embodiment of a patient monitoring system 100 isillustrated. The patient monitoring system 100 includes a patientmonitor 102 attached to a sensor 106 by a cable 104. The sensor monitorsvarious physiological data of a patient and sends signals indicative ofthe parameters to the patient monitor 102 for processing. The patientmonitor 102 generally includes a display 108, control buttons 110, and aspeaker 112 for audible alerts. The display 108 is capable of displayingreadings of various monitored patient parameters, which may includenumerical readouts, graphical readouts, and the like. Display 108 may bea liquid crystal display (LCD), a cathode ray tube (CRT), a plasmascreen, a Light Emitting Diode (LED) screen, Organic Light EmittingDiode (OLED) screen, or any other suitable display. A patient monitoringsystem 102 may monitor oxygen saturation (SpO2), perfusion index (PI),pulse rate (PR), hemoglobin count, and/or other parameters. Anembodiment of a patient monitoring system according to the presentdisclosure is capable of measuring and displaying total hemoglobintrending data and preferably is capable of conducting data analysis asto the total hemoglobin trending.

FIG. 2 illustrates details of an embodiment of a patient monitoringsystem 100 in a schematic form. Typically a sensor 106 includes energyemitters 216 located on one side of a patient monitoring site 218 andone or more detectors 220 located generally opposite. The patientmonitoring site 218 is usually a patient's finger (as pictured), toe,ear lobe, or the like. Energy emitters 216, such as LEDs, emitparticular wavelengths of energy through the flesh of a patient at themonitoring site 218, which attenuates the energy. The detector(s) 220then detect the attenuated energy and send representative signals to thepatient monitor 102.

Specifically, an embodiment of the patient monitor 102 includesprocessing board 222 and a host instrument 223. The processing board 222includes a sensor interface 224, a digital signal processor (DSP) 226,and an instrument manager 228. In an embodiment of the disclosure, theprocessing board also includes a fast Fourier transform (FFT) module232. In an embodiment, the FFT module 232 can comprise a special-purposeprocessing board or chip, a general purpose processor runningappropriate software, or the like. The FFT module 232 may further beincorporated within the instrument manager 228 or be maintained as aseparate component (as illustrated in FIG. 2).

The host instrument typically includes one or more displays 108, controlbuttons 110, a speaker 112 for audio messages, and a wireless signalbroadcaster 234. Control buttons 110 may comprise a keypad, a fullkeyboard, a track wheel, and the like. Additionally embodiments of apatient monitor 102 can include buttons, switches, toggles, check boxes,and the like implemented in software and actuated by a mouse, trackball,touch screen, or other input device.

The sensor interface 224 receives the signals from the sensor 106detector(s) 220 and passes the signals to the DSP 226 for processinginto representations of physiological parameters. These are then passedto the instrument manager 228, which may further process the parametersfor display by the host instrument 223. In some embodiments, the DSP 226also communicates with a memory 230 located on the sensor 106; suchmemory typically contains information related to the properties of thesensor that may be useful in processing the signals, such as, forexample, emitter 216 energy wavelengths. The elements of processingboard 222 provide processing of the sensor 106 signals. Tracking medicalsignals is difficult because the signals may include various anomaliesthat do not reflect an actual changing patient parameter. Strictlydisplaying raw signals or even translations of raw signals could lead toinaccurate readings or unwarranted alarm states. The processing board222 processing generally helps to detect truly changing conditions fromlimited duration anomalies. The host instrument 223 then is able todisplay one or more physiological parameters according to instructionsfrom the instrument manager 228, and caregivers can be more confident inthe reliability of the readings.

In an embodiment, the patient monitor 102 keeps track of totalhemoglobin data over a period of time, such as a few minutes, a fewhours, a day or two, or the like. It is important to monitor totalhemoglobin over a range of time because it has been discovered thathemoglobin fluctuates over time. In an embodiment, the instrumentmanager may include a memory buffer 234 to maintain this data forprocessing throughout a period of time. Memory buffer 234 may includeRAM, Flash or other solid state memory, magnetic or optical disk-basedmemories, combinations of the same or the like. The data for totalhemoglobin over a period of time can then be passed to host instrument223 and displayed on display 108. In an embodiment, such a display mayinclude a graph such as that illustrated by FIG. 3. FIG. 3 illustrates asample tHb trend graph measuring tHb in g/dL over a period ofapproximately 80 minutes. In an embodiment, a patient monitor 102 mayperiodically or continuously update the total hemoglobin display to showthe previous hour, previous 90 minutes, or some other desirable timeperiod.

Displaying a current total hemoglobin count, as well as data for a priortime period helps allow a caregiver to determine if the current count iswithin a normal range experienced by the individual patient. It has alsobeen found that the variations in total hemoglobin count are generallycyclic. It is preferable to display a time period that encompasses atleast one complete tHb cycle. As such, a caregiver will be quickly ableto see if a total hemoglobin count has fallen above or below thepatient's general cyclic range. Additionally, the caregiver may also beable to see if the patient's total hemoglobin count is rising or fallingabnormally.

In an embodiment, the trending of the total hemoglobin is additionallyor alternatively analyzed through, for example, a frequency domainanalysis to determine patterns in the patient hemoglobin fluctuation.Total hemoglobin data from the instrument manager 228 or its memorybuffer 234 is passed to the FFT module 232, in an embodiment, toaccomplish such an analysis. The FFT module uses one of a number of fastFourier transform algorithms to obtain the frequencies of various totalhemoglobin readings. The resulting data can be graphed and displayed bythe host instrument 223's display(s) 108, as shown by example in FIG. 4.

In an embodiment, both total hemoglobin graphs and frequency domainanalysis can be displayed on a single patient monitor display 108. In anembodiment, a button 110 or other control allows switching between twosuch display states. In other embodiments, the display 108 may changeautomatically, such as periodically or based on a specific event, suchas an abnormal change in a patient's total hemoglobin count.

The frequency domain analysis can determine a specific patient signaturefor a patient, in an embodiment, because the frequency variations havebeen found to be unique or semi-unique between different patients. Assuch, a portion of the memory buffer 234 may maintain a baseline totalhemoglobin frequency data set for comparison to later data readings fromthe sensor 106. Changes in the frequency analysis may indicate a changein a monitored patient's status. In such an embodiment, a baselinereference graph and a more current frequency domain analysis may begraphed together on a single graph display, on multiple proximate graphdisplays or display windows, or the like to allow caregivers torecognize changes in the patient's hemoglobin levels over time. Forexample, in an embodiment, a single graph may include both sets of datagraphed in different colors, such as a blue baseline reading and a greenmore current reading frequency analysis. Variations between the two may,in an embodiment, trigger an alert or an alarm if they reach a certainthreshold. Such an alert or alarm may be audible and output throughaudible indicator 112 and/or may alter the display 108. The alarm oralert may incorporate changing colors, flashing portions of a screen,text or audible messages, audible tones, combinations of the same or thelike.

FIG. 5 illustrates an embodiment of a method of obtaining, analyzing,and displaying total hemoglobin data for patient status and analysis asgenerally described herein. Starting with block 540, energy istransmitted through patient tissue at a measurement site, generally by asensor 106. The patient tissue attenuates the energy which is thendetected at block 542. The detected signals are evaluated to determine acurrent total hemoglobin count (block 546). This step may include, in anembodiment, filtering noise from the signals, filtering errant readings,and the like. In an embodiment, a buffer stores the total hemoglobinreadings for a period of time in (block 548). This allows the patientmonitor to display trending data, display the total hemoglobin readingsfor a period of time, rather than just relatively instantaneousreadings, and the like. In an embodiment, the patient monitor analyzesthe set of buffered total hemoglobin readings using a Fourier transform,such as a discrete Fourier transform, or more preferably one of manysuitable fast Fourier transform algorithms (block 550). This analysisdecomposes the sequence of total hemoglobin readings into components ofdifferent frequencies. Displaying this frequency analysis (block 552)can help caregivers identify changing conditions for a patient that mayindicate worsening or improving health conditions.

The display of trending total hemoglobin data and caregiverunderstanding of a patient's condition that comes with understandingsuch a display are important uses. The automatic interpretation of thisdata into patient care is another. FIGS. 6 and 7 illustrate exemplarysystems incorporating uses for patient monitoring of a patient's totalhemoglobin in treating the patient for various ailments or injuries. Forexample, studies have shown that one of the most recurrent problems ofhemodialysis is anemia—a condition in which a patient's blood lackssufficient red blood cells. Dialysis-dependent patients can improvetheir quality of life by maintaining an adequate hemoglobin level. Tothis end, it may be advantageous to link the patient monitoring ofhemoglobin levels to a dialysis machine to provide hemoglobin levelfeedback, allowing the dialysis machine to act intelligently and helpregulate hemoglobin levels during dialysis. An embodiment of such asystem is illustrated in FIG. 6.

As illustrated, an embodiment of the patient monitor 102 is set up inmuch the same way as described above, with a cable 104 attaching to anoninvasive sensor 106 located proximal to a patient measurement site,such as the finger shown in FIG. 6. An additional cable 660 connectsdialysis machine 662 to the patient monitor 102. The dialysis machine662 generally includes an arterial line 664 and a venous line 664, eachof which end in needles 668 for insertion into a patient's artery andvein, respectively. Dialysis machine 662 may then operate at least inpart based on hemoglobin levels of the patient as determined by thepatient monitor 102. As the hemoglobin levels naturally change, in anembodiment, patient monitor 102 may simply signal the dialysis machinewhen hemoglobin levels are approaching or have fallen outside of maximumand minimum ranges. Alternatively, the patient monitor 102 may passhemoglobin level readings to the dialysis machine 662 continuously, atgenerally periodic intervals, upon changes in hemoglobin level readings,or the like. The dialysis machine 662 can then alter its processing ofthe blood, inject appropriate amounts of drugs, turn off or on, orotherwise change states or processes based in whole or in part on thehemoglobin levels detected.

FIG. 7 illustrates another exemplary use for patient monitoring of apatient's total hemoglobin in treating the patient for various ailmentsor injuries. In the embodiment shown, an IV fluid bag is connected tothe patient monitor by tubing 772. The patient monitor 102 thenincorporates a venous line 664 ending in a needle 668 for insertion intoa patient's vein. IVs are often used to administer nutrition, drugs,blood, plasma, and other transfusions, and the like. The patient monitor102 may thus incorporate a device to control the rate or amount of IVfluid administered to a patient. In the embodiment illustrated, thepatient monitor controls the administration, at least in part, based onthe hemoglobin levels detected.

As one example, erythropoiesis-stimulating agents (ESAs) are drugs thatcan help encourage the production of red blood cells. The patientmonitor 102 can use the hemoglobin readings of a monitored patient tocontrol the administration of such a drug through an IV. Similarly, thepatient monitor can increase the transfusion of blood to a patient if,for example, hemoglobin levels fall below the normal range ofhemoglobin. Monitoring the hemoglobin levels with knowledge of thenatural fluctuation of those levels in the patient can help reduce theamounts of drugs administered, blood or other fluids transfused, and thelike. For example, the patient monitor can help keep the hemoglobinlevels in a normal range rather than trying to maintain an exact level,which may lead to less efficient treatment. For example, a fallinghemoglobin level may still be within natural limits and may rise withoutadditional treatment. In an embodiment, the patient monitor 102 canwithhold treatment in such a situation and provide additional treatmentif the hemoglobin is predicted to fall outside or is outside normallimits. This can help reduce the usage of costly treatments and/orconserve those in short supply. Additionally, it may be important tolimit usage of a drug due to increased risks of side effects, drugdependency, or the like.

Of course, the foregoing are exemplary only and any IV administereddrug, blood, plasma, nutrition, other fluid, or the like that has atendency to affect hemoglobin levels can be administered and controlledin this manner. One of skill in the art will also understand that thepatient monitor and administration devices can be incorporated in asingle unit (such as illustrated in FIG. 7) or occur in wired orwirelessly communicating separate units (such as illustrated in FIG. 6)in various embodiments. Administration devices can include not only IVcontrolling units and dialysis machines as discussed, but other devicesdesigned to aid in providing something of need to a patient. Similarly,other patient parameters detected by sensor 106 and calculated bypatient monitor 102 may also be passed to administration devices or usedinternally to affect the administration of drugs, blood, nutrition,other fluid, or the like.

Hemoglobin concentration can be affected by a variety of differentphysiological factors, including abnormalities of the hemoglobin or thered blood cells that carry the hemoglobin, vessel fluid volume changesor other physiological factors. For example, fluid volume in the vesselis constantly changing as fluid can enter or exit the blood cell throughthe arteries. As concentration of hemoglobin is generally determined bythe amount of hemoglobin divided by the amount of volume of fluid in theblood cells, changes in the vessel volume will directly affect thehemoglobin concentration. For example, standing up or changing positioncan alter the hydrostatic affect of blood pressure on the arteries,potentially changing the concentration of total hemoglobin in the blood.

Another exemplary use for patient monitoring of a patient's totalhemoglobin involves monitoring these various physiological factors thatcan affect the total hemoglobin concentration and determining whenvariations are normal or can indicate physiological problems orabnormalities. For example, in some embodiments differences in the fluidvolume based on permeability or other factors that affect the vesselfluid volume can have an effect on the total hemoglobin concentration inthe blood. In one embodiment, fluctuations in the permeability of theblood vessels and ion balance can cause the influx our excretion offluid from the blood vessels causing changes in the hemoglobinconcentration. These changes can be normal or periodic changes that canbe identified as such through specific algorithms or can be abnormalchanges in the permeability that can trigger an alarm during patientmonitoring. Also, changes in the rate of hemoglobin production over timecan have an effect on the hemoglobin concentration that can be monitoredor taken into account. Further, changes in the spleen function,including in its capacity to remove dead or damages red blood cells fromthe blood stream, can produce changes in the total hemoglobinconcentration.

Another exemplary use for patient monitoring of a patient's totalhemoglobin related to physiological processes or abnormalities involvesdetermining an abnormality or type of hemoglobin that can be present inthe blood. For example, in some embodiments, certain types ordeformations of the hemoglobin or red blood cells may cause the totalhemoglobin value in a patient's arteries to vary with time or varylocally in certain parts of the arteries. For example, sickle cellanemia, a condition characterized by sickle shaped red blood cells, maycause red blood cells to clump together. This or other abnormalities inthe cells may cause local or global variation in the amount ofhemoglobin, as a clump of red blood cells may be more dense that adispersed group of red blood cells, or alter the permeability or abilityof the red blood cells to enter the micro circulation. Sometimes, thered blood cells of a person with sickle cell anemia can have difficultydeforming and therefore fitting through vessels in the microcirculation. This can cause them to bunch up near the smaller bloodvessels in the micro circulation and change the concentration ofhemoglobin. Therefore, this abnormality may exhibit a somewhat normal orpredictable cyclical change or frequency of variation in the hemoglobinof the blood and therefore monitoring the total hemoglobin may aid inthe diagnosis of these types of conditions. Also, it can cause thehemoglobin concentration to be abnormally low or high in some cases. Inother embodiments, various other red blood cell or hemoglobinabnormalities may cause regular variation in the total hemoglobin thatmay be used to assist in the diagnosis of these ailments, including forexample, Thalassemia.

Various data can be collected from patients with hemoglobin and redblood cell abnormalities to determine or identify any potentialsignatures or unique or predicable fluctuations in the hemoglobinlevels. This data can be used to diagnose patients by comparing apatient's hemoglobin variability to that of data from normal patientsand from patients with certain abnormalities. This can provide anon-invasive method of screening for certain abnormalities that mayotherwise require invasive blood testing by drawing blood and testing itin the lab or other time consuming and costly methods of analysis. Also,knowledge about the physiological processes that cause normal variationin the hemoglobin concentration can increase the ability to screennormal from abnormal variation in the hemoglobin by analyzing totalhemoglobin data over time.

For example, in an embodiment, a caregiver can set up the patientmonitor 102 to obtain signals from a patient representative of the totalhemoglobin of the patient over time. The patient monitor 102 can thensend the signals to the processing board 222 to be analyzed andprocessed to determine whether or not the signals or data from thepatient is representative of a patient with a hemoglobin abnormalitysuch as sickle cell anemia or are indicative of normal variation in thehemoglobin concentration. In an embodiment, the signals can be comparedto existing data from patients that have been confirmed to have sicklecell anemia to determine if the condition likely exists in the currentpatient based on similarity of hemoglobin variability. In anotherembodiment, the signals can be filtered and processed to look forcertain signal components that may be indicative of an abnormality suchas sickle cell anemia.

Although the foregoing has been described in terms of certain specificembodiments, other embodiments will be apparent to those of ordinaryskill in the art from the disclosure herein. Moreover, the describedembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of other formswithout departing from the spirit thereof. Accordingly, othercombinations, omissions, substitutions, and modifications will beapparent to the skilled artisan in view of the disclosure herein. Forexample, various functions described as occurring in FFT module 232 maybe incorporated within other portions of the processing board 222.Similarly, a patient monitor 102 may not have a distinct processingboard 222 and host instrument 223; instead, the various functionsdescribed herein may be accomplished by different components within apatient monitor 102 without departing from the spirit of the disclosure.Thus, the present disclosure is not limited by the preferredembodiments, but is defined by reference to the appended claims. Theaccompanying claims and their equivalents are intended to cover forms ormodifications as would fall within the scope and spirit of thedisclosure.

1. (canceled)
 2. A patient monitoring system comprising: a light emitterconfigured to emit energy into a tissue site of a patient; a detectorconfigured to detect a response from the tissue site responsive to theemission of energy into the tissue site of the patient; one or morehardware processors configured to: determine a plurality of hemoglobinconcentration measurements over time for the tissue site based on thedetected response; perform a frequency transform on the plurality ofhemoglobin concentration measurements; and display a plurality offrequency components on a display screen of a patient monitor based onthe performed frequency transform of the plurality of hemoglobinconcentration measurements.
 3. The patient monitoring system of claim 2,wherein the one or more hardware processors are further configured todetermine an oxygen saturation of blood flow into the tissue site basedon the detected response.
 4. The patient monitoring system of claim 3,wherein the oxygen saturation is displayed on the display screen.